Attenuation of NK cells facilitates mammary tumor growth in streptozotocin-induced diabetes in mice

Diabetic patients have higher incidence and mortality of cancer. Recent study revealed that hyperglycemia-induced oxidative stress is involved in the acceleration of tumor metastasis. We used model of high-dose streptozotocin-induced diabetes to investigate its effect on tumor growth and modulation of antitumor immune response of 4T1 murine breast cancer in BALB/c mice. Diabetes accelerated tumor appearance, growth and weight, which was associated with decreased NK cells cytotoxicity against 4T1 tumor cells in vitro. Diabetes reduced frequencies of systemic NKG2D+, perforin+, granzyme+, IFN-+ and IL-17+ NK cells, while increased level of PD-1 expression and production of IL-10 in NK cells. Diabetes decreased percentage of NKG2D+NK cells and increased percentage of PD-1+ NK cells also in primary tumor. Diabetes increased accumulation of IL-10+ Tregs and TGF-β+ myeloid-derived suppressor cells (MDSCs) in spleen and tumor. Diabetic sera in vitro significantly increased the percentage of KLRG-1+ and PD-1+ NK cells, decreased the percentage of IFN-+NK cells, expression of NKp46 and production of perforin, granzyme, CD107a and IL-17 per NK cell in comparison to glucose-added mouse sera and control sera. Significantly increased percentages of inducible nitric oxide synthase (iNOS) and indoleamine 2,3-dioxygenase (IDO) producing MDSCs and dendritic cells (DC) were found in the spleens of diabetic mice prior to tumor induction. 1-methyl-DL-tryptophan, specific IDO inhibitor, almo...
Source: Endocrine-Related Cancer - Category: Endocrinology Authors: Tags: Research Source Type: research